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refactor(windows-host): delete the SudoVDA backend — pf-vdisplay is the sole vdisplay (Goal 2)

Browse Source 
Goal 2 ("drop every trace of SudoVDA") is done. The SudoVDA driver is no longer
shipped (only pf-vdisplay; the old vdisplay-driver tree was deleted in a2bd0cd),
and F1 (d638a93/e60cda3) already moved the display-utility helpers out of the
backend into neutral modules (win_adapter/win_display), breaking the reach-in.
So the backend is now cleanly removable:

- Deleted crates/punktfunk-host/src/vdisplay/windows/sudovda.rs (350 lines: the
  SudoVdaDisplay VirtualDisplay impl + its VdisplayDriver/probe).
- vdisplay::open()/probe() are now unconditional pf-vdisplay; deleted the
  windows_use_pf_vdisplay() backend selector. open() now ensure!s
  pf_vdisplay::is_available() with a clear "driver not installed" error instead
  of the old silent SudoVDA fallback (no fallback driver exists anymore).
- Scrubbed the dangling references to the deleted symbols (manager/sendinput/dxgi
  comments, the config + host.env PUNKTFUNK_VDISPLAY docs); the var stays as an
  informational forward-seam. Updated the F1 module docs (Goal 2 now done).

All changes are #[cfg(windows)] except the config doc; Linux clippy
-p punktfunk-host -D warnings clean; zero `sudovda::`/`SudoVdaDisplay` code refs
remain (comments only). Windows build is CI-gated.

Scorecard Goal 2 -> DONE; recorded the E1 "do NOT do it" stability decision in
windows-host-rewrite.md §4 (the process-global driver design is sound given
ProcessSharingDisabled; a device-owned variant adds a use-after-free window for
no gain).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
This commit is contained in:
Enrico Bühler
2026-06-25 22:35:42 +00:00
parent 8cde8621ce
commit 84a3b95f17
10 changed files with 50 additions and 405 deletions
Download Patch File Download Diff File Expand all files Collapse all files
crates/punktfunk-host/src/capture/windows/dxgi.rs
+3 -3
View File
@@ -2186,9 +2186,9 @@ impl DuplCapturer {
let context = context.context("null D3D11 context")?;
// 3) duplicate the output. Attach to the current input desktop first (as SYSTEM this can
// be the Winlogon secure desktop) so a session that starts at the lock/login screen works.
// The SudoVDA is kept the sole desktop via the CCD isolation in sudovda::create_monitor
// (registry-persisted), so the secure desktop has nowhere to render but the output we
// capture — no per-open re-isolation needed.
// The virtual display is kept the sole desktop via the CCD isolation the pf-vdisplay backend
// applies at monitor creation (registry-persisted), so the secure desktop has nowhere to render
// but the output we capture — no per-open re-isolation needed.
attach_input_desktop();
let dupl = duplicate_output(&output, &device, want_hdr)
.context("DuplicateOutput (already duplicated by another app?)")?;
crates/punktfunk-host/src/config.rs
+3 -1
View File
@@ -72,7 +72,9 @@ pub struct HostConfig {
pub compositor: Option<String>,
/// `PUNKTFUNK_GAMEPAD` — client/operator virtual-pad backend preference (fed to `pick_gamepad`).
pub gamepad: Option<String>,
/// `PUNKTFUNK_VDISPLAY` — Windows virtual-display backend select (`pf`/`pfvd` vs `sudovda`; else auto-detect).
/// `PUNKTFUNK_VDISPLAY` — Windows virtual-display backend. The pf-vdisplay IddCx driver is now the only
/// backend (the legacy SudoVDA backend was removed), so this is currently informational — kept for the
/// shipped `host.env` and as a forward seam if a second backend is ever added.
pub vdisplay: Option<String>,
}
crates/punktfunk-host/src/inject/windows/sendinput.rs
+1 -1
View File
@@ -35,7 +35,7 @@ pub struct SendInputInjector {
desktop: Option<HDESK>,
}
// Only ever used from the host's single injector thread (like SudoVdaDisplay).
// Only ever used from the host's single injector thread.
unsafe impl Send for SendInputInjector {}
impl SendInputInjector {
crates/punktfunk-host/src/vdisplay.rs
+9 -28
View File
@@ -529,15 +529,15 @@ pub fn open(compositor: Compositor) -> Result<Box<dyn VirtualDisplay>> {
}
#[cfg(target_os = "windows")]
{
// Two virtual-display backends: the new pf-vdisplay IddCx driver (pf_vdisplay_proto) and the
// shipping SudoVDA fallback. The compositor arg is moot on Windows. PUNKTFUNK_VDISPLAY overrides;
// default auto-detects (prefer pf-vdisplay if its driver interface is present).
// The pf-vdisplay all-Rust IddCx driver is the sole virtual-display backend (the legacy SudoVDA
// fallback was removed — its driver is no longer shipped). The compositor arg is moot on Windows.
let _ = compositor;
if windows_use_pf_vdisplay() {
Ok(Box::new(pf_vdisplay::PfVdisplayDisplay::new()?))
} else {
Ok(Box::new(sudovda::SudoVdaDisplay::new()?))
}
anyhow::ensure!(
pf_vdisplay::is_available(),
"pf-vdisplay driver interface not found — the pf-vdisplay IddCx driver is not installed or \
not loaded (the host installer bundles it; reinstall or check the driver state)"
);
Ok(Box::new(pf_vdisplay::PfVdisplayDisplay::new()?))
}
#[cfg(not(any(target_os = "linux", target_os = "windows")))]
{
@@ -546,18 +546,6 @@ pub fn open(compositor: Compositor) -> Result<Box<dyn VirtualDisplay>> {
}
}
/// Pick the Windows virtual-display backend. `PUNKTFUNK_VDISPLAY=pf|pf-vdisplay|pfvd` forces the new
/// pf-vdisplay IddCx driver; `=sudovda|sudo` forces the shipping SudoVDA driver; anything else (the
/// default) auto-detects, preferring pf-vdisplay if its device interface is enumerable.
#[cfg(target_os = "windows")]
fn windows_use_pf_vdisplay() -> bool {
match crate::config::config().vdisplay.as_deref().map(str::trim) {
Some("pf") | Some("pf-vdisplay") | Some("pfvd") => true,
Some("sudovda") | Some("sudo") => false,
_ => pf_vdisplay::is_available(),
}
}
/// Readiness probe for `compositor`: is it up and able to create a virtual output *right
/// now*? A session-bringup script polls this (via `punktfunk-host probe-compositor`) to gate
/// on actual readiness instead of racing the compositor with a blind sleep.
@@ -578,11 +566,7 @@ pub fn probe(compositor: Compositor) -> Result<()> {
#[cfg(target_os = "windows")]
{
let _ = compositor;
if windows_use_pf_vdisplay() {
pf_vdisplay::probe()
} else {
sudovda::probe()
}
pf_vdisplay::probe()
}
#[cfg(not(any(target_os = "linux", target_os = "windows")))]
{
@@ -640,9 +624,6 @@ pub(crate) mod manager;
#[cfg(target_os = "windows")]
#[path = "vdisplay/windows/pf_vdisplay.rs"]
pub(crate) mod pf_vdisplay;
#[cfg(target_os = "windows")]
#[path = "vdisplay/windows/sudovda.rs"]
pub(crate) mod sudovda;
#[cfg(target_os = "linux")]
#[path = "vdisplay/linux/wlroots.rs"]
mod wlroots;
crates/punktfunk-host/src/vdisplay/windows/manager.rs
+1 -1
View File
@@ -178,7 +178,7 @@ impl VirtualDisplayManager {
}
/// Open + initialise the backend (validates the driver is present). Mirrors the old
/// `SudoVdaDisplay::new`/`PfVdisplayDisplay::new`.
/// `PfVdisplayDisplay::new`.
pub(crate) fn open_backend(&self) -> Result<()> {
// Hold the state lock across the open so two racing backends can't double-open the device.
let _guard = self.state.lock().unwrap();
crates/punktfunk-host/src/vdisplay/windows/sudovda.rs
-350
View File
@@ -1,350 +0,0 @@
//! Windows virtual-display backend driving **SudoVDA** (the SudoMaker Virtual Display Adapter —
//! the Indirect Display Driver the Apollo Sunshine-fork ships). The Windows analogue of the
//! Linux per-compositor backends: [`create`](VirtualDisplay::create) adds a virtual monitor at the
//! client's exact `WxH@Hz` (the mode is baked into the ADD IOCTL — no EDID seeding), starts the
//! mandatory watchdog ping, and the returned [`VirtualOutput`]'s keepalive `Drop` removes it (RAII).
//!
//! Control surface (verified live against SudoVDA 0.2.1): a device-interface-GUID + `CreateFileW`
//! + `DeviceIoControl` IOCTL protocol. No DLL, no named pipe. See `docs/windows-host.md`.
use std::ffi::c_void;
use std::mem::size_of;
use std::os::windows::io::{FromRawHandle, OwnedHandle};
use std::sync::atomic::Ordering;
use anyhow::{Context, Result};
use windows::core::{GUID, PCWSTR};
use windows::Win32::Devices::DeviceAndDriverInstallation::{
SetupDiDestroyDeviceInfoList, SetupDiEnumDeviceInterfaces, SetupDiGetClassDevsW,
SetupDiGetDeviceInterfaceDetailW, DIGCF_DEVICEINTERFACE, DIGCF_PRESENT,
SP_DEVICE_INTERFACE_DATA, SP_DEVICE_INTERFACE_DETAIL_DATA_W,
};
// (CCD `Devices::Display` + `Graphics::Gdi` imports moved with the display helpers to `win_display`.)
use windows::Win32::Foundation::{CloseHandle, HANDLE, LUID};
use windows::Win32::Storage::FileSystem::{
CreateFileW, FILE_FLAGS_AND_ATTRIBUTES, FILE_SHARE_READ, FILE_SHARE_WRITE, OPEN_EXISTING,
};
use windows::Win32::System::IO::DeviceIoControl;
use super::manager::{AddedMonitor, MonitorKey, VdisplayDriver};
use super::{Mode, VirtualDisplay, VirtualOutput};
// SudoVDA device-interface GUID (Common/Include/sudovda-ioctl.h).
const SUVDA_INTERFACE: GUID = GUID::from_u128(0xE5BC_C234_1E0C_418A_A0D4_EF8B_7501_414D);
// CTL_CODE(FILE_DEVICE_UNKNOWN=0x22, func, METHOD_BUFFERED=0, FILE_ANY_ACCESS=0).
const fn ctl(func: u32) -> u32 {
(0x22u32 << 16) | (func << 2)
}
const IOCTL_ADD: u32 = ctl(0x800);
const IOCTL_REMOVE: u32 = ctl(0x801);
const IOCTL_SET_RENDER_ADAPTER: u32 = ctl(0x802); // == 0x0022_2008
const IOCTL_GET_WATCHDOG: u32 = ctl(0x803);
/// pf-vdisplay extension (NOT in SudoVDA): tear down every virtual monitor. Sent once on host startup
/// to reap monitors orphaned by a crashed/killed previous host. SudoVDA returns invalid (ignored).
const IOCTL_CLEAR_ALL: u32 = ctl(0x804);
const IOCTL_DRIVER_PING: u32 = ctl(0x888);
const IOCTL_GET_VERSION: u32 = ctl(0x8FF);
/// A UNIQUE-per-session SudoVDA monitor GUID. The monitor is keyed by GUID for IOCTL_ADD/REMOVE, so a
/// FIXED GUID makes overlapping sessions (a client reconnecting after a freeze before the old session
/// has torn down, or genuine concurrent sessions) all map to the SAME monitor — then one session's
/// IOCTL_REMOVE on teardown tears the monitor down OUT FROM UNDER a still-live session ("display
/// disconnected" sound + freeze, even with no context change — observed live). Make it unique per
/// (process, session): base GUID with the low 48-bit node = (pid << 16 | session#).
fn next_monitor_guid() -> GUID {
use std::sync::atomic::AtomicU32;
static N: AtomicU32 = AtomicU32::new(0);
let n = N.fetch_add(1, Ordering::Relaxed) as u128;
let pid = std::process::id() as u128;
GUID::from_u128(0x70756E6B_7466_756E_6B30_000000000000u128 | (pid << 16) | (n & 0xFFFF))
}
#[repr(C)]
#[derive(Clone, Copy)]
struct AddParams {
width: u32,
height: u32,
refresh: u32,
guid: GUID,
device_name: [u8; 14],
serial: [u8; 14],
}
#[repr(C)]
#[derive(Clone, Copy)]
struct AddOut {
luid: LUID,
target_id: u32,
}
// SET_RENDER_ADAPTER input — byte-identical to SudoVDA's `{ LUID AdapterLuid; }` (8 bytes). The
// windows `LUID` is `{ LowPart: u32, HighPart: i32 }` == the C `LUID`, so `#[repr(C)]` is exact.
#[repr(C)]
#[derive(Clone, Copy)]
struct SetRenderAdapterParams {
luid: LUID,
}
/// Pin the SudoVDA IDD's RENDER GPU to `luid` (Apollo's `SetRenderAdapter`). No output buffer. MUST be
/// issued on the driver handle BEFORE `IOCTL_ADD` to steer which GPU the new target renders on — on a
/// multi-adapter box (SudoVDA IDD + a discrete GPU) this stops DXGI from reparenting the virtual
/// output onto a different adapter than the one we duplicate/encode on (the ACCESS_LOST storm).
unsafe fn set_render_adapter(h: HANDLE, luid: LUID) -> Result<()> {
let p = SetRenderAdapterParams { luid };
let bytes = std::slice::from_raw_parts(
&p as *const _ as *const u8,
size_of::<SetRenderAdapterParams>(),
);
let mut none: [u8; 0] = [];
ioctl(h, IOCTL_SET_RENDER_ADAPTER, bytes, &mut none)
.map(|_| ())
.context("SudoVDA SET_RENDER_ADAPTER")
}
#[repr(C)]
struct RemoveParams {
guid: GUID,
}
/// One `DeviceIoControl` round trip (METHOD_BUFFERED). `input`/`output` may be empty.
unsafe fn ioctl(h: HANDLE, code: u32, input: &[u8], output: &mut [u8]) -> Result<u32> {
let mut returned = 0u32;
let inp = (!input.is_empty()).then_some(input.as_ptr() as *const c_void);
let outp = (!output.is_empty()).then_some(output.as_mut_ptr() as *mut c_void);
DeviceIoControl(
h,
code,
inp,
input.len() as u32,
outp,
output.len() as u32,
Some(&mut returned),
None,
)
.with_context(|| format!("DeviceIoControl(code={code:#x})"))?;
Ok(returned)
}
unsafe fn open_device() -> Result<HANDLE> {
let hdev = SetupDiGetClassDevsW(
Some(&SUVDA_INTERFACE),
PCWSTR::null(),
None,
DIGCF_DEVICEINTERFACE | DIGCF_PRESENT,
)
.context("SetupDiGetClassDevsW(SudoVDA) — is the SudoVDA driver installed?")?;
let mut idata = SP_DEVICE_INTERFACE_DATA {
cbSize: size_of::<SP_DEVICE_INTERFACE_DATA>() as u32,
..Default::default()
};
SetupDiEnumDeviceInterfaces(hdev, None, &SUVDA_INTERFACE, 0, &mut idata)
.context("SetupDiEnumDeviceInterfaces(SudoVDA)")?;
let mut required = 0u32;
let _ = SetupDiGetDeviceInterfaceDetailW(hdev, &idata, None, 0, Some(&mut required), None);
let mut buf = vec![0u8; required as usize];
let detail = buf.as_mut_ptr() as *mut SP_DEVICE_INTERFACE_DETAIL_DATA_W;
(*detail).cbSize = size_of::<SP_DEVICE_INTERFACE_DETAIL_DATA_W>() as u32;
SetupDiGetDeviceInterfaceDetailW(hdev, &idata, Some(detail), required, None, None)
.context("SetupDiGetDeviceInterfaceDetailW(SudoVDA)")?;
let handle = CreateFileW(
PCWSTR((*detail).DevicePath.as_ptr()),
0xC000_0000, // GENERIC_READ | GENERIC_WRITE
FILE_SHARE_READ | FILE_SHARE_WRITE,
None,
OPEN_EXISTING,
FILE_FLAGS_AND_ATTRIBUTES(0),
None,
)
.context("CreateFileW(SudoVDA device)")?;
let _ = SetupDiDestroyDeviceInfoList(hdev);
Ok(handle)
}
/// The SudoVDA IOCTL surface behind the shared [`VirtualDisplayManager`](super::manager::VirtualDisplayManager)
/// (Goal-1 §2.5) — the only SudoVDA-specific code left; the monitor lifecycle is the shared state machine.
pub(crate) struct SudoVdaDriver;
impl VdisplayDriver for SudoVdaDriver {
fn name(&self) -> &'static str {
"sudovda"
}
unsafe fn open(&self) -> Result<(OwnedHandle, u32)> {
let device = unsafe { open_device()? };
let mut ver = [0u8; 4];
if unsafe { ioctl(device, IOCTL_GET_VERSION, &[], &mut ver) }.is_ok() {
tracing::info!(
"SudoVDA protocol {}.{}.{} (test={})",
ver[0],
ver[1],
ver[2],
ver[3]
);
}
let mut wd = [0u8; 8];
let watchdog_s = if unsafe { ioctl(device, IOCTL_GET_WATCHDOG, &[], &mut wd) }.is_ok() {
u32::from_le_bytes([wd[0], wd[1], wd[2], wd[3]]).max(1)
} else {
3
};
tracing::info!("SudoVDA watchdog timeout {}s", watchdog_s);
// Reap monitors orphaned by a crashed previous host (SudoVDA returns invalid for CLEAR_ALL —
// ignored; pf-vdisplay honors it).
let mut none: [u8; 0] = [];
if unsafe { ioctl(device, IOCTL_CLEAR_ALL, &[], &mut none) }.is_ok() {
tracing::info!("cleared orphaned virtual monitors on host startup");
}
// Take ownership — the OwnedHandle CloseHandle's the control device on drop (it was leaked before).
Ok((unsafe { OwnedHandle::from_raw_handle(device.0 as _) }, watchdog_s))
}
unsafe fn add_monitor(
&self,
dev: HANDLE,
mode: Mode,
render_luid: Option<LUID>,
) -> Result<AddedMonitor> {
// SET_RENDER_ADAPTER (opt-in). On this box SudoVDA IGNORES the pin and the IDD lands on a different
// adapter than its DXGI output is enumerated under — the cross-GPU ACCESS_LOST source — so the
// manager only pins under PUNKTFUNK_RENDER_ADAPTER / IDD-push.
if let Some(luid) = render_luid {
match unsafe { set_render_adapter(dev, luid) } {
Ok(()) => tracing::info!(
luid = format!("{:08x}:{:08x}", luid.HighPart, luid.LowPart),
"SudoVDA SET_RENDER_ADAPTER: pinned IDD render GPU"
),
Err(e) => tracing::warn!("SudoVDA SET_RENDER_ADAPTER failed (continuing): {e:#}"),
}
}
let mut device_name = [0u8; 14];
let nm = b"punktfunk";
device_name[..nm.len()].copy_from_slice(nm);
let session_guid = next_monitor_guid();
let add = AddParams {
width: mode.width,
height: mode.height,
refresh: mode.refresh_hz,
guid: session_guid,
device_name,
serial: [0u8; 14],
};
let add_bytes = unsafe {
std::slice::from_raw_parts(&add as *const _ as *const u8, size_of::<AddParams>())
};
let mut out = [0u8; size_of::<AddOut>()];
unsafe { ioctl(dev, IOCTL_ADD, add_bytes, &mut out) }.with_context(|| {
format!(
"SudoVDA ADD {}x{}@{}",
mode.width, mode.height, mode.refresh_hz
)
})?;
let ao = unsafe { *(out.as_ptr() as *const AddOut) };
tracing::info!(
"SudoVDA created {}x{}@{} (target_id={}, adapter_luid={:#x})",
mode.width,
mode.height,
mode.refresh_hz,
ao.target_id,
ao.luid.LowPart
);
if let Some(luid) = render_luid {
if ao.luid.LowPart == luid.LowPart && ao.luid.HighPart == luid.HighPart {
tracing::info!("SudoVDA ADD render adapter matches the pinned GPU (pin took)");
} else {
tracing::warn!(
add = format!("{:08x}:{:08x}", ao.luid.HighPart, ao.luid.LowPart),
pinned = format!("{:08x}:{:08x}", luid.HighPart, luid.LowPart),
"SudoVDA ADD render adapter DIFFERS from pinned — driver ignored SET_RENDER_ADAPTER?"
);
}
}
Ok(AddedMonitor {
key: MonitorKey::Guid(session_guid),
target_id: ao.target_id,
luid: ao.luid,
})
}
unsafe fn remove_monitor(&self, dev: HANDLE, key: &MonitorKey) -> Result<()> {
let MonitorKey::Guid(guid) = key else {
anyhow::bail!("sudovda: unexpected monitor key kind");
};
let rp = RemoveParams { guid: *guid };
let rp_bytes = unsafe {
std::slice::from_raw_parts(&rp as *const _ as *const u8, size_of::<RemoveParams>())
};
let mut none: [u8; 0] = [];
unsafe { ioctl(dev, IOCTL_REMOVE, rp_bytes, &mut none) }.map(|_| ())
}
unsafe fn ping(&self, dev: HANDLE) -> Result<()> {
let mut none: [u8; 0] = [];
unsafe { ioctl(dev, IOCTL_DRIVER_PING, &[], &mut none) }.map(|_| ())
}
}
/// The Windows SudoVDA virtual-display backend. A marker — the lifecycle lives in the shared
/// [`VirtualDisplayManager`](super::manager::VirtualDisplayManager).
pub struct SudoVdaDisplay;
impl SudoVdaDisplay {
pub fn new() -> Result<Self> {
super::manager::init(Box::new(SudoVdaDriver)).open_backend()?;
Ok(Self)
}
}
impl VirtualDisplay for SudoVdaDisplay {
fn name(&self) -> &'static str {
"sudovda"
}
fn create(&mut self, mode: Mode) -> Result<VirtualOutput> {
super::manager::vdm().acquire(mode)
}
}
/// Readiness probe: can we open the SudoVDA control device?
pub fn probe() -> Result<()> {
let h = unsafe { open_device()? };
unsafe {
let _ = CloseHandle(h);
}
Ok(())
}
/// Is the SudoVDA driver present (device interface enumerable)?
pub fn is_available() -> bool {
unsafe { open_device().map(|h| CloseHandle(h)).is_ok() }
}
#[cfg(test)]
mod tests {
use super::*;
use std::thread;
use std::time::Duration;
/// Live hardware round trip — skipped unless `PUNKTFUNK_SUDOVDA_LIVE=1` (needs the SudoVDA
/// driver installed). Exercises the real trait path: open -> create -> hold -> drop (REMOVE).
#[test]
fn live_create_drop() {
if std::env::var("PUNKTFUNK_SUDOVDA_LIVE").is_err() {
return;
}
let mut vd = SudoVdaDisplay::new().expect("open SudoVDA");
let vout = vd
.create(Mode {
width: 1920,
height: 1080,
refresh_hz: 60,
})
.expect("create virtual display");
assert_eq!(vout.preferred_mode, Some((1920, 1080, 60)));
thread::sleep(Duration::from_secs(3));
drop(vout); // triggers REMOVE + stops the pinger
}
}
crates/punktfunk-host/src/windows/win_adapter.rs
+2 -2
View File
@@ -3,8 +3,8 @@
//! The discrete render-GPU LUID picker used to live in the SudoVDA backend (`vdisplay::sudovda`) — a
//! historical accident, since it is display-utility, not SudoVDA-specific. It lives here so the capturers
//! (IDD-push) and the pf-vdisplay backend depend on it as a *peer* instead of reaching into the SudoVDA
//! module — breaking that circular reach-in so SudoVDA can eventually be dropped without losing this
//! helper (audit §9 / Goal 2). This is the plan's `windows/adapter.rs`.
//! module — breaking that circular reach-in, which let the SudoVDA backend be dropped without losing this
//! helper (audit §9 / Goal 2 — done). This is the plan's `windows/adapter.rs`.
use windows::Win32::Foundation::LUID;
crates/punktfunk-host/src/windows/win_display.rs
+2 -2
View File
@@ -5,8 +5,8 @@
//! These are display-utility, NOT SudoVDA-specific (a pf-vdisplay monitor's target_id is a real OS target
//! id, so they operate identically), so they live here rather than in the SudoVDA backend — breaking the
//! circular reach-in where the capturers + the pf-vdisplay backend reached into `vdisplay::sudovda` for
//! them, so SudoVDA can eventually be dropped without losing them (audit §9 / Goal 2). The plan's
//! `windows/display_ccd.rs`. Moved verbatim from `vdisplay::sudovda`.
//! them, which let the SudoVDA backend be dropped without losing them (audit §9 / Goal 2 — done). The
//! plan's `windows/display_ccd.rs`. Extracted verbatim from the former SudoVDA backend before its removal.
use std::mem::size_of;